The expected announcement by George Osborne that his budget on Wednesday will include higher taxes on "millionaire's mansions" has its own significance in Scotland.

Within a year or two, Scotland will be setting its own stamp duty on house sales, raising the intriguing prospect that the country's millionaire bankers, expatriate estate owners, oil tycoons and Highland lairds will be paying different rates to their English and Welsh counterparts.

In a deal to placate his Lib Dem coalition partners, Osborne is expected to announce that houses selling for more than £2m will pay a higher rate of stamp duty, up from 5% to 7%, in return for scrapping the 50p top rate of income tax.

According to new data given to the Guardian, these sales were worth up to £56m a year in Scotland at the height of the property boom.

To give the budget a further twist, only a few hours before the chancellor was due to get to his feet in the House of Commons it emerged that the Scottish government has agreed to the UK government's offer to devolve stamp duty.

Thanks to Osborne's proposals, that is now one of the more eye-catching elements in the Scotland bill's relatively limited proposals to devolve control over income tax rates, along with aggregates levy and the landfill levy.

The deal sees Alex Salmond suddenly drop his repeated demands for much more significant financial powers, in what is doubtless a tactical move by the first minister in advance of the independence referendum.

But it is worth looking closely at what that could mean for Scotland. The question now facing the first minister is whether he keeps this upper rate for mansions, or sets a new lower or higher rate tax. Who does he want to appeal to: financiers and company directors, or middle-earning voters?

According to data supplied by Registers of Scotland (RoS), in the good years, Osborne's proposals will affect property sales in excess of £50m a year. But the data shows that mansion sales are, unsurprisingly, highly volatile.

The RoS data shows that since 2003, nearly 90 mansions worth more than £2m have sold, at a total value of more than £215m.

Those sales reached their peak in 2007 and 2008, when 22 houses worth more than £2m were sold in each of those years, chiefly in Edinburgh. In 2007, that generated £56m in total sales, and in 2008, £52m.

But that was at the height of the property bubble, which was punctured with devastating effect by the banking crisis and the global recession, which particularly hit Edinburgh's then booming banking and finance sector.

In 2009, the total sales fell to a third of their previous level, to seven, with a total value of £17.6m. In 2011, that rose somewhat to nearly £27m for houses worth over £2m, with four of those sold in oil-rich Aberdeen.

So, as a rough rule of thumb, in Scotland the Treasury could only earn an extra £540,000 from raising stamp duty by 2% based on last year's sales figures. That won't buy much.

So if the Scottish government does want to use stamp duty to raise more revenues from higher earners, it'll likely be those buying homes in the £1m bracket who should feel a little jumpy. There were 138 of those last year across Scotland, a far more lucrative number to look at.

Despite Scotland's global reputation for its prestigious Highland estates and castles, Scottish property is not terribly valuable compared to the UK average, which is heavily skewed by London and Home County property prices.

According to the Office of Budget Responsibility, Scottish property values are worth only three quarters of the UK average,

It will publish its predictions of stamp duty land tax (SDLT) incomes under the Scotland bill later on Wednesday, but had this to say about the proportion of Scottish stamp duty receipts compared to the UK total earlier in March:

The share has varied between 3.8 per cent and 6.7 per cent over the past six years. With the average property price in Scotland below the UK average and with just over three quarters of the UK yield coming from properties over £250,000, the Scottish share of SDLT receipts is below the Scottish share of UK GDP.

It said that last year £330m was raised by stamp duty in Scotland, from residential and commercial property, but that was only a 5.5% share of the UK total. That was due largely to commercial property hitting 8.6%, more than Scotland's population share. On a more sobering note, private property stamp duty only came in at 4.1% or £165m.

So, for the Scottish government, they may feel justified in arguing that devolving stamp duty to Holyrood isn't actually a very significant concession at all by Cameron's government, since Holyrood spends more than £30bn a year.

At these levels, it hardly gives the Scottish parliament heavy financial firepower. But then, the UK government could argue that this means greater cross-subsidy by the Treasury to Scotland, to pay for the raising of the basic rate tax starting threshold closer to the Lib Dems £10,000 target.